Private Content Routing with Cryptography

Creator

Nicola

Created

Jul 7, 2022 1:25 PM

Stage

Graduated from Notebook

Goals:

• Privacy of what content
• Privacy of who is storing it

Approach 1: Clear text setting

• Setup: Indexer has in clear text all the map(content → sp)
• Client requests in an oblivious way the key(content) value(sps) that they are interest in

Approach 2: Encrypted text setting

• Setup: SP sends an encrypted list of content to the indexer. (indexer doesn’t know what content the SP is storing)
• (somehow) Indexer has many encrypted lists (in a way that query in these list)
• Client request a search in all the sp indeces

Question:

• Can we have multiple indexers and assuming that they are not colluding? (This is important for PIR)

Additional resources:

• A similar setting: https://arxiv.org/pdf/2005.14645.pdf
• On FHE emulating PIR through "projection functions". See, e.g., page 10 here (“f_proj”):
• https://eprint.iacr.org/2022/638.pdf
• I.e.:

Client(i)

• makes ct <- Enc_pk(i) Sends ct to Server
• Server: ct_response <- FHE.Eval(pk, f_ proj, ct) where f_proj_D(i) -> D_i D1, … D_N is DB
• more on PIR in general:
• http://course.ece.cmu.edu/~ece733/lectures/20-pir.pdf
• Recent PIR paper with amortized efficiency:
• eprint.iacr.org/2022/081

Strategy:

• Leak no info requires the indexer reading the entire database